Force Resolution for Moonlight-qt GUI

[SchwingMC]

Is your feature request related to a problem? Please describe.
I'm using Moonlight-qt on a Raspberry Pi 4 with a LibreElec-RR build (here and here) on a 4k TV. For performance reasons I want to run kodi at 1080@60, which works perfectly fine, however, if I run Moonlight the resolution switches to 4k@30. If I opt for 1080@60 in the Moonlight settings, the stream is incoming at 1080 with 60 fps, but the TV resolution is still at 4k@30, which causes tearing on the screen.

Describe the solution you'd like
An option to force the Moonlight gui to run at a specific resolution would be nice.

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
I already tried to force this on libreelec side by adding video=HDMI-A-1:1920x1080@60D and drm.edid_firmware=HDMI-A-1:edid/edid-HDMI-A-1.bin video=HDMI-A-1:1920x1080D to cmdline.txt, but this doesn't work.
Additional context
Add any other context or screenshots about the feature request here.

[LATINO-BICEPS]

Hey I'm struggling with the same issue as you with the GUI defaulting to the highest resolution the TV supports. I'm wondering if you had any workarounds/fixes since then?

[SchwingMC]

Hi, yes I have a workaround for libreelec.
But I must inform you that this kills CEC functions (you won't be able to use your TV remote to control libreelec) and HDMI audio.
If you want to try it anyway, add
drm.edid_firmware=HDMI-A-1:edid/1920x1080.bin video=HDMI-A-1:D to cmdline.txt. Be sure to add it at the end of cmdline.txt, make NO extra line.
Greetings

[LATINO-BICEPS]

No HDMI audio is such a dealbreaker for me. Nice that you found a solution for your use case regardless.

On a related note, I was digging into the QT docs and got the GUI to run at 1080p60 by running QT_QPA_PLATFORM=linuxfb:size=1920x1080 moonlight-qt. Slight problem, I have awful lines zapping across the screen but it is not too bad.

[xanarin]

I ran into this same issue after getting a new TV on Black Friday. I was seeing stutters in my 1080p60 stream because the display was actually running at 4K30. I was able to work around it by adding the following lines to my /boot/config.txt:

# Force HDMI to do 1080p60 (even though the TV supports higher)
hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=69

The first line tells the Pi to ignore the resolutions that the TV reports (over EDID) that it supports. This causes my Pi 4 to only use the resolution/mode that I set in the last two lines: 1080p @ 60Hz. More details on these options can be found in the elinux RPiconfig documentation.

Audio over HDMI still works, but I'm unsure of whether CEC works (because I don't have a great way to test it). The one drawback is that it causes text elements in the Moonlight GUI to become much larger than they should, however once streaming starts everything works very smoothly.

Screenshots taken with raspi2png

[awoelfl]

My setup:

• 4k@30 TV (Samsung 2016 Model)
• Raspberry PI 4
• LibreELEC 10
• Moonlight QT 3.2.0 (compiled via Docker, see https://github.com/veldenb/plugin.program.moonlight-qt)
• HVEC enabled by dtoverlay=rpivid-v4l2

I got it working by combining @LATINO-BICEPS and @SchwingMC approaches. In a nutshell, I configured the "shell-resolution" in cmdline.txt and export QT_QPA_PLATFORM before launching moonlight.

Detailed steps:

• Make cmdline.txt editable by executing mount -o rw,remount /flash
• Execute nano /flash/cmdline.txt and append video=HDMI-A-1:1920x1080M-32@60:mD to the kernel line (i.e., the first line), see https://www.kernel.org/doc/Documentation/fb/modedb.txt. Do NOT (!!) set drm.edid_firmware!
• Execute nano /storage/.kodi/addons/plugin.program.moonlight-qt/resources/bin/bootstrap_moonlight-qt.sh and add export QT_QPA_PLATFORM=linuxfb:size=1920x1080 as second line after the shebang !#/bin/bash

This way i got CEC, audio, and 60fps in moonlight working. Note that the change in cmdline.txt does not force the resolution to 1080p, Kodi is still able to switch to 2160p when playing 4k content.

[SchwingMC]

There seems to be an update on the Moonlight side of things. Due to the build I'm using I can't edit moonlight-qt.sh (I'm using LibreELEC-RR from SupervisedThinking). So I created a new image from recent source. Only cmdline.txt was edited in the way @awoelfl is suggesting. Now the Moonlight user interface is in 4k, but the actual streaming content is displayed in 1080*60 if this is selected in the moonlight options. Also CEC and HDMI audio are working.

[cgutman]

Yep, I enabled switching into 1080p60 here: e56bb67

So that's fixed in Moonlight v3.2.0.

[arnerak]

There seems to be an update on the Moonlight side of things. Due to the build I'm using I can't edit moonlight-qt.sh (I'm using LibreELEC-RR from SupervisedThinking). So I created a new image from recent source. Only cmdline.txt was edited in the way @awoelfl is suggesting. Now the Moonlight user interface is in 4k, but the actual streaming content is displayed in 1080*60 if this is selected in the moonlight options. Also CEC and HDMI audio are working.

Unfortunately this is not the case for me. The moonlight-qt.log file suggests the correct resolution was picked but the TV still reports 4K@30.
00:00:15 - SDL Info (0): Chosen best display mode: 1920x1080x60
Adding the QT environment variable that @LATINO-BICEPS was suggesting makes moonlight-qt crash on launch. All I can see regarding this in the log is floating point exception. Without the change to /flash/cmdline.txt moonlight-qt launches, but only moonlight-qt's render size is changed, not the screen resolution:

The suggestion from @xanarin doesn't work for me either, I can still see all TV resolutions inside LibreElec's settings and moonlight-qt will launch in 4K.
LibreElec does work fine with 1080p@60.

[SchwingMC]

You have to start an app, for example the Desktop or the game you want to play. It should then be started in 1080p.

[awoelfl]

hm i can confirm the issue described by @arnerak. Screen resolution stays at 4k with the new 4.0.0 version

[arnerak]

To make it work for 4.0.0 I had to

• append video=HDMI-A-1:1920x1080M-32@60:mD to /flash/cmdline.txt
• add export QT_QPA_PLATFORM=linuxfb:size=1920x1080 to bootstrap_moonlight-qt.sh
• change QT_SCALE_FACTOR=0.93 to QT_SCALE_FACTOR=1.0 in bootstrap_moonlight-qt.sh for moonlight-qt to not crash on launch (not a real fix, the gui looks awful now)

[cgutman]

Sounds like a possible SDL bug, since the behavior shouldn't have changed between v3.2.0 and v4.0.0. Can you post logs from moonlight after streaming?

[awoelfl]

@arnerak thank you for sharing, setting the scale to 1 works for me as well
@cgutman please find attached logs for:

• moonlight-scale-1-1080.log: with QT_QPA_PLATFORM=linuxfb:size=1920x1080 and QT_SCALE_FACTOR=1.0
• moonlight-scale-0.93-1080.log: with QT_QPA_PLATFORM=linuxfb:size=1920x1080 and QT_SCALE_FACTOR=0.93(crashes)
• moonlight-scale-0.93-4k.log: with QT_SCALE_FACTOR=0.93

However, the scaling factor is set by a kodi addon (https://github.com/veldenb/plugin.program.moonlight-qt) in my case. Git blame revealed that the scaling factor was added in a rather recent commit (veldenb/plugin.program.moonlight-qt@d28988e). My current hypothesis is that the feature didn't break because of the update of moonlight-qt but because of an update of the kodi addon. So nothing you guys need to tackle?

moonlight-scale0.93-4k.log
moonlight-scale0.93-1080.log
moonlight-scale1-1080.log
.